Method and device for threading a web in the reeling of a paper or board web

ABSTRACT

A web is threaded in the reeling of a paper or board web, by passing a web tail strip (W) into a reeling nip between a reeling drum ( 10 ) and a reel spool ( 12 ), on which a web roll is formed. The tail strip (W) is passed into the reeling nip by a suction zone ( 20 ) which extends substantially around the entire reeling drum circumference and is ( 10 ) in an area where a full-width web runs during reeling, so that the tail strip (w) can be conducted directly along the suction zone ( 20 ). The suction zone ( 20 ) is placed in the longitudinal direction of the reeling drum ( 10 ), i.e. in the width direction of the web.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a U.S. national stage application of internationalapplication No. PCT/FI2003/000595, filed Aug. 7, 2003, the disclosure ofwhich is incorporated by reference herein and claims priority on FinnishApplication No. 20021459, Filed Aug. 9, 2002.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

As known in the prior art, in connection with the reeling of a paperweb, a reeling drum is used which is provided with suction zones of thesector type, i.e. suction takes place through holes situated in asuction drum shell only in part of the circumference of the drum in thearea of a certain sector. One prior-art arrangement in the reeling of apaper web, using a reeling drum provided with a suction zone sector, isdisclosed in FI patent 74446. In known arrangements in which the suctionzone is formed into a sector, it is hardly at all possible to remove theboundary layer air flow produced by the rotating drum. In addition, thesuction zone sector in known applications is situated outside the web inthe length direction of the drum, i.e. in the width direction of theweb, and for this reason during threading it has been necessary to guidethe tail strip to the side, i.e. to the zone area, by means of blowing.In many cases, the location of the suction zone sector is also notoptimal on the circumference of the drum because the tail striptypically misses the area of the suction sector in the threadingoperation. If the tail strip misses the suction zone, the tail stripslips out of the machine to the tending side, thus not entering the nipbetween the reeling drum and the reel spool, i.e. a holding/pullingpoint. The strip may also be directed towards the middle of the machineand it may slip into the nip from some unpredictable point. This leadsto a random amount of loose strip. The tightening of the loose striplengthens the time taken by threading unnecessarily. In many cases itdoes not even succeed, but breaks when it flaps and flutters into otherstructures of the machine. After unsuccessful threading attempts, thethreading path must be cleared to remove broken tail strips in orderthat new attempts may be made, which in turn further increases thethreading time unnecessarily. The arrangement known from FI patent 74446is primarily intended to aid reeling in order that the reeling speedmight be increased, when needed. This known arrangement does not teachthreading of a web.

In the arrangements known from the prior art, the holes through which asuction effect is arranged to be produced, are generally placed in theridges between the grooves of grooved drums.

With respect to the state of the art relating to the threading of apaper web in connection with finishing devices, reference may be made,for example, to FI patent 98742, which discloses a method and anapparatus for threading a paper web on a surface treatment line forpaper. In this known arrangement, the paper guide rolls and the surfacetreatment roll of the surface treatment line are provided with a suctionsector and a blow sector, and by using them it is possible to cause thetail strip to adhere reliably to the perforated surface of the roll bymeans of the suction sector, and by means of suction it is possible toassure the right direction of the draw of the tail strip as well as theguidability of the draw, and formation of an air film between the paperweb and the roll is avoided by means of the blow sector, and the tailstrip is separated from the roll surface by means of blowing.

With respect to the prior art, reference can also be made to U.S. Pat.No. 5,915,648 disclosing a perforated roll for guiding a flexiblematerial web, in particular a paper web, which has a jacket and a hollowinterior and a respective cover at each end of the jacket. The jackethas a plurality of passage openings for passage of air therethrough, andat least one impeller inside the interior of the roll having a suctionside for drawing air into the roll through the passage openings.

SUMMARY OF THE INVENTION

An object of the invention is to create a method and a device forthreading a web in connection with the reeling of a paper or board web,in which method and device the drawbacks of the known arrangementsdescribed above are eliminated or at least minimized.

A particular object of the invention is to create an arrangement which,when used, enables the tail strip to adhere very well to the reelingdrum and ensures that the tail strip is guided to the reeling nip.

A further object of the invention is to provide an arrangement whichenables the tail strip to be positioned in the suction zone of thereeling drum both in the circumferential direction and in the lateraldirection.

In accordance with the invention, a suction zone is arranged inconnection with a reeling drum, which suction zone extends over theentire circumference of the drum and is located in the area of the webin the width direction of the web, i.e. in the longitudinal direction ofthe drum, so that the tail strip of the web will also be positioned inthe suction zone area also in the lateral direction without a transferaccomplished by means of blowings or the like. The strip is sought to bebrought to the holding point as tight as possible, that is withoutlooseness.

In accordance with an advantageous feature of the arrangement of theinvention, the apertures for achieving a suction effect, i.e. suctionholes, are arranged at the bottom of the grooves of a grooved drum, mostappropriately with close spacing. By this means, the boundary layersproduced by the rotating drum and the moving web can be eliminated orreduced so as to be insignificant, with the result that the threadingoperation takes place reliably.

In an arrangement in accordance with an advantageous embodiment of theinvention, the boundary layer produced during one revolution of thereeling drum is removed during the same revolution and, at the sametime, the air amount carried with the tail strip is sucked. In thatconnection, the air amount sucked through the suction zone preferablyexceeds the air amount carried in the boundary layer of the drum, sothat by means of this so-called oversucking of the boundary layer it isassured that a vacuum effect, i.e. a lower static pressure, extendsbeyond the boundary layer, whereby the tail strip can be brought closerto the drum and caused to adhere to the surface of the reeling drum. Theair carried with the tail strip is also sucked by means of thisso-called oversucking.

In the arrangement in accordance with the invention, the tail strip canbe made to adhere to the reeling drum in a reliable manner and the tailstrip goes into the nip in a reliable manner. When, in accordance withthe invention, the suction zone is disposed within the web area in thewidth direction of the web, the tail strip can be brought to the suctionzone of the reeling drum without a lateral shift, which means that noseparate means are needed for moving the tail strip in the lateraldirection. In addition, in the arrangement in accordance with theinvention, the tail strip is always positioned in the suction zone inthe circumferential direction because the suction zone extends over theentire circumference.

In accordance with an advantageous embodiment of the invention, suctionholes are arranged at the bottom of the grooves, so-called ventagrooves, provided in the drum, so that the paper adheres to the surfaceof the drum because in entering the nip there is no discontinuity in thepressure prevailing in the groove. By so placing the holes at the bottomof the groove, the force holding the web against the drum surface can bemade greater because the area of the groove against the web is largerthan that of a single hole. After the web has adhered to the surface ofthe drum, the pressure in the groove is roughly of the same order as inthe case where the web would cover one hole.

In accordance with advantageous additional features of the invention,the width of the suction zone in the longitudinal direction of the drum,i.e. in the width direction of the web, is smaller than the width of theweb, advantageously 2-4 times the width of the tail strip, the distancebetween the suction holes in the circumferential direction of thereeling drum is about 10-100 mm, preferably 15-25 mm, and the diameterof the suction apertures is 1-10 mm, advantageously 2-4 mm, the groovesof the reeling drum are, for example, 1-3 mm wide, typically 1.5-2.5 mmwide, and the depth of the grooves is 1-8 mm, typically 3.5-4.5 mm, andthe distance between the grooves is 5-100 mm, typically 6-25 mm. Thespeed of air in the holes of the suction zone is 20-200 m/s,advantageously 50-100 m/s, and the air sucked through the suction zoneis conducted out from a hole situated in the axle of the reeling drum orin another appropriate manner. The air is passed from the end of theaxle along a tube to a blower or, alternatively, the air can be drawnfrom the end of the drum through the flange of the drum by means of aseparate suction box, from which it is passed to a blower. Generally,the suction zone is at either edge of the paper machine in the area of aroll end, but it can also be situated on an arbitrary line between theedges of the machine.

In the following, the invention will be described in greater detail withreference to the figures in the appended drawings, but the invention isnot by any means meant to be narrowly limited to the details of thesefigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a tail strip threading situation on a reel-upin accordance with one advantageous exemplifying embodiment of theinvention.

FIG. 2A is a schematic view of a reeling drum used in accordance withone exemplifying embodiment of the invention.

FIG. 2B schematically shows a partial enlargement of the area A in FIG.2A.

FIG. 2C is a schematic partial cross-sectional view of a nip between areeling drum and a reel spool.

FIG. 3 schematically shows a boundary layer in a reel-up.

FIG. 4 schematically shows a measurement result relating to boundarylayers of a reeling drum.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the schematic view of the embodiment shown in FIG. 1, a tail strip Wis passed in a threading situation in a reel-up via a paper guide roll11 or equivalent to a reeling drum 10, on which it adheres to thesurface of the reeling drum 10 by means of a suction zone 20 of thereeling drum 10 and by means of the suction zone 20 the web is passed toa reeling nip between the reeling drum 10 and a reel spool 12, fromwhich nip the tail strip is turned onto the reel spool 12 to start a newreeling operation. Belt conveyors 15, 16, the operation of which is initself known by a person skilled in the art, are arranged in thevicinity of the paper guide roll 11 for conducting the tail strip W. Asuction tube 13 leads from one end of the reeling drum 10 to a blower 14to produce a suction zone in the suction zone 20 by means of suctionprovided from inside the reeling drum. The suction zone 20 is placed inthe reeling drum 10 in the longitudinal direction of the reeling drum10, i.e. in the width direction of the web, in the area where afull-width web runs in the normal running situation (not shown).

As shown in FIG. 2A, the reeling drum 10 comprises ends 17, 18, and areeling drum shell (not shown), with space remaining inside it, isdisposed around an axle between the ends 17,18. The suction zone 20 ofthe reeling drum 10 is placed in the vicinity of one end 17 of thereeling drum at a distance from the end 17 but in that area where thefull-width web runs. The other end of the reeling drum 10 is denotedwith the reference numeral 18.

In the schematic partial view of FIG. 2A shown in FIG. 2B, the area Ashows that the suction zone 20 comprises grooves 21, i.e. so-calledventa grooves, and suction holes 22 through which a suction effect isprovided for the suction zone area on the surface of the reeling drum10. As shown in FIG. 2B, the suction holes 22 are placed at the ventagrooves 21.

It is seen in the schematic partial view of FIG. 2C from the area of thesuction zone 20 of the reeling drum 10, when the reeling drum 10 forms anip with the reel spool 12, that the grooves 21 extend to a certaindepth from the surface of the reeling drum 10 and the suction apertures,or the suction holes 22, are placed at the grooves 21, which suctionholes extend through the shell of the reeling drum 10 to the inside ofthe shell of the reeling drum 10 to transmit a suction effect to thesurface of the reeling drum 10.

FIG. 3 schematically shows in a reel-up a boundary layer L which isformed in the reel-up in the area of the reeling drum 10 and the reelspool 12, which boundary layer is controlled in a threading situation bymeans of a suction zone in accordance with the invention such that theamount of air sucked through the suction zone exceeds the amount of aircarried in the boundary layer L of the drum, thereby assuring a suctioneffect, i.e. a lower static pressure on the surface of the drum and inits vicinity, so that the tail strip can be brought closer to the drumand caused to adhere to the surface of the drum. The air carried withthe tail strip is also sucked by means of the suction effect. In FIG. 3,a web guide roll is denoted with the reference numeral 19.

FIG. 4 shows some schematic measurement results relating to a boundarylayer produced on a reeling drum in a trial situation in which the speedwas 1500 m/min and when a pressure difference was effective over thereeling drum shell and when there was no pressure difference over thereeling drum shell. The curve 31 represents a situation when thepressure difference was 0 and the curve 32 represents a situation whenthe pressure difference was 270 Pa. The X axis represents the distancefrom the drum surface and the Y axis represents the speed of air inunits m/s.

Above, the invention has been described only with reference to some ofits advantageous exemplifying embodiments, to the details of which theinvention is, however, not meant to be narrowly limited.

1. A reeling device for threading a web in the reeling of a paper orboard web, comprising: a reeling drum, having a drum interior and acylindrical reeling surface, portions of the cylindrical surface formingan area where a full-width web of a first selected width is arranged torun during reeling, the cylindrical surface defining a circumference; asource of lower static pressure outside the reeling drum; a reel spoolforming a nip with the reel drum, the reel spool arranged to receive thepaper or board web from the portions of the cylindrical surface formingan area where a full-width web is arranged to run, to form a web roll;portions of the reeling drum forming a plurality of suction aperturesextending between the drum interior and the reeling surface to provide asuction effect on the surface of the reeling drum, the suction aperturesforming a suction zone which extends around the entire circumference ofthe reeling drum, and wherein the suction zone forms a part of theportions of the cylindrical surface forming the area where a full-widthweb is arranged to run during reeling; and wherein the drum interior isconnected to the source of a lower static pressure outside the reelingdrum by a tube connected to a hole situated in an axle of the reelingdrum, the lower static pressure selected so that the suction zone holdsa tail threading strip of a second selected width, cut from the paper orboard web full width.
 2. The device of claim 1, wherein the portions ofthe cylindrical surface forming an area where a full-width web isarranged to run during reeling form a plurality of circumferentialgrooves spaced along an axis defined by the cylindrical reeling surface;and wherein the suction apertures of the suction zone are situated atsaid grooves and in said grooves.
 3. The device of claim 1 wherein thecircumference of the cylindrical reeling surface defines acircumferential direction, and wherein the suction zone has a widthtransverse to the circumferential direction which is smaller than thefirst selected width of the web.
 4. The device of claim 1 wherein thesuction zone has a width which is two to four times the second selectedwidth of the tail threading strip.
 5. The device of claim 1 wherein thereeling drum has a first end of the reeling drum and a second end of thereeling drum and the cylindrical reeling surface positionedtherebetween, and wherein the suction zone is closely spaced from one ofthe first end or the second end of the reeling drum.
 6. The device ofclaim 1, wherein the source of a lower static pressure outside thereeling drum is a blower connected to the interior by the tube connectedto the hole situated in an axle of the reeling drum, and through whichhole and tube, air is transported to the blower.
 7. The device of claim1, wherein the source of a lower static pressure outside the reelingdrum is connected though an end of the reeling drum by a suction box. 8.A reeling device for threading a web in the reeling of a paper or boardweb, comprising: a reeling drum, having a drum interior and acylindrical reeling surface, portions of the cylindrical surface formingan area where a full-width web of a first selected width is arranged torun during reeling, the cylindrical surface defining a circumference; areel spool forming a nip with the reel drum, the reel spool arranged toreceive the paper or board web from the portions of the cylindricalsurface forming an area where a full-width web is arranged to run, toform a web roll; portions of the reeling drum forming a plurality ofsuction apertures extending between the drum interior and the reelingsurface to provide a suction effect on the surface of the reeling drum,the suction apertures forming a suction zone which extends around theentire circumference of the reeling drum, and wherein the suction zoneforms a part of the portions of the cylindrical surface forming the areawhere a full-width web is arranged to run during reeling; wherein thedrum interior is connected to a source of a lower static pressureoutside the reeling drum, the lower static pressure selected so that thesuction zone holds a tail threading strip of a second selected width,cut from the paper or board web full width; and wherein thecircumference of the cylindrical reeling surface defines acircumferential direction, and the suction apertures of the suction zoneare arranged with 15-25 mm spacing in the circumferential direction, and6-25 mm spacing transverse to the circumferential direction.
 9. Areeling device for threading a web in the reeling of a paper or boardweb, comprising: a reeling drum, having a drum interior and acylindrical reeling surface, portions of the cylindrical surface formingan area where a full-width web of a first selected width is arranged torun during reeling, the cylindrical surface defining a circumference; areel spool forming a nip with the reel drum, the reel spool arranged toreceive the paper or board web from the portions of the cylindricalsurface forming an area where a full-width web is arranged to run, toform a web roll; portions of the reeling drum forming a plurality ofsuction apertures extending between the drum interior and the reelingsurface to provide a suction effect on the surface of the reeling drum,the suction apertures forming a suction zone which extends around theentire circumference of the reeling drum, and wherein the suction zoneforms a part of the portions of the cylindrical surface forming the areawhere a full-width web is arranged to run during reeling; wherein thedrum interior is connected to a source of a lower static pressureoutside the reeling drum, the lower static pressure selected so that thesuction zone holds a tail threading strip of a second selected width,cut from the paper or board web full width; and wherein thecircumference of the cylindrical reeling surface defines acircumferential direction, and the distance between the suctionapertures in the circumferential direction of the reeling drum is about10-100 mm, and the diameter of the suction apertures is 1-10 mm.
 10. Amethod for threading a web in the reeling of a paper or board web,comprising the steps of: passing a tail threading strip cut from a paperor board web into a reeling nip between a reeling drum having acircumferential surface, and a reel spool, to form a web roll on thereel spool; conducting the tail threading strip on the circumferentialsurface of the reeling drum and passing the paper or board web into saidreeling nip between the reeling drum and the reel spool by attachment ofthe tail threading strip to a suction zone of the reel drum whichextends entirely around the circumferential surface of the reel drum sothat the tail threading strip is conducted directly along the suctionzone situated on the circumferential surface of the reeling drum in anarea where a full-width web runs during reeling; drawing air through aplurality of suction apertures 1-10 mm in diameter, said aperturesextending between an interior of the drum and the circumferentialsurface and connected to a source of a lower static pressure outside thereeling drum, wherein the air is drawn through said apertures at a speedof 20-200 m/s to provide the suction effect on the circumferentialsurface of the reeling drum, the suction apertures forming the suctionzone; and wherein a boundary layer of air, produced by the rotatingreeling drum and motion of the tail threading strip is substantiallyremoved by a suction effect provided through the suction zone.
 11. Themethod of claim 10, wherein the tail strip of the web is conducted tothe reeling nip by the suction zone and wherein the suction zone issituated closely spaced from one end of the reeling drum.
 12. The methodof claim 10, wherein the circumferential surface has portions forming aplurality of circumferential grooves spaced along an axis defined by thecircumferential surface, and wherein the suction apertures of thesuction zone are situated at said grooves and in said grooves.
 13. Themethod of claim 10 wherein the circumference of the cylindrical reelingsurface defines a circumferential direction, and wherein the suctionzone has a width transverse to the circumferential direction which is2-4 times the width of the tail threading strip, and the suction zonehas a width transverse to the circumferential direction which is smallerthan the area where the full-width web runs during reeling.
 14. Themethod of claim 10 wherein the reeling drum has a first end of thereeling drum and a second end of the reeling drum and the cylindricalreeling surface is positioned therebetween, and wherein the suction zoneis closely spaced from one of the first end or the second end of thereeling drum.
 15. The method of claim 10 wherein the air is drawnthrough said apertures at a speed of 50-100 m/s to provide the suctioneffect on the circumferential surface of the reeling drum, the suctionapertures forming the suction zone.
 16. The method of claim 10, whereinthe source of a lower static pressure outside the reeling drum isconnected through an end of the reeling drum by a suction box.